Which metal burn in air at high temperature with the evolution of much heat

Which one is a pseudo alum

Which of the following compounds is formed by addition of mineral acid to an aqueous solution of borax?

The gaseous product $(s)$ expected at room temperature by reaction of sodium borohydride and boron trifluoride under anhydrous conditions is/are:

The electrochemical extraction of aluminum from bauxite ore involves.

$(A)$ the reaction of $Al _2 O _3$ with coke ($C$) at a temperature $>2500^{\circ} C$.

$(B)$ the neutralization of aluminate solution by passing $CO _2$ gas to precipitate hydrated alumina $\left( Al _2 O _3 .3 H _2 O \right)$

$(C)$ the dissolution of $Al _2 O _3$ in hot aqueous $NaOH$.

$(D)$ the electrolysis of $Al _2 O _3$ mixed with $Na _3 AlF _6$ to give $Al$ and $CO _2$.

The compound($s$) which react($s$) with $NH _3$ to give boron nitride ($BN$) is(are)

$(A)$ $B$ $(B)$ $B _2 H _6$ $(C)$ $B _2 O _3$ $(D)$ $HBF _4$